The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Motor vehicles typically include an engine system that produces drive torque that is transmitted through a transmission to a drivetrain to drive wheels of the vehicle. The engine system may include an internal combustion engine that combusts an air and fuel mixture within cylinders to drive pistons, which produces the drive torque. Air flow into engines is regulated via a throttle. More specifically, the throttle adjusts throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders. Increasing the amount of air and fuel provided to the cylinders increases the torque output of the engine.
Engine control systems have been developed to control engine torque output to achieve a desired torque. The desired torque may be based on one or more driver inputs, such as an accelerator pedal position. The engine control systems may include one or more electronic control modules that control engine torque output by controlling operation of one or more actuators, such as a throttle actuator that controls the throttle to achieve the desired torque. The electronic control modules may control operation based on one or more operating conditions of the engine, such as engine speed. During periods when the driver removes his or her foot from the accelerator pedal, such as when the vehicle is idling or coasting down from a higher speed, the electronic control modules may control engine torque output to achieve a desired engine idle speed.